Conventionally, a seat for a vehicle including a reclining apparatus is configured by right and left cushion frames for supporting a seat cushion, right and left seatback frames which support a seat back and which are rotatable relatively to the cushion frames, and a reclining apparatus interposed between each of the cushion frames and each of the seat back frames for adjusting a rotational position of the seat back frames (refer to patent document JP2004-330991A).
The reclining apparatus described in the patent document includes a lower arm fixed to a cushion frame, an upper arm which is rotatably attached to the lower arm and which is rotatable with a seat back frame, the lower arm to which the upper arm is rotatably attached, and a lock member. The lock member is operated to switch, at the time when the rotational position of the seat back frame is adjusted within a range of seating positions, between a locked state, in which rotation of the upper arm is locked, and a lock-released state, in which the lock of the rotation of the upper arm is released.
Then, the reclining apparatus includes a ratchet (a rotating member for forward-tilting) interposed between the upper arm and the seat back frame in order for operating the seat back to tilt forward (walk-in operation) in a state where a position of a reclining angle adjustment is memorized, at the time when an occupant enters or exits from a seat which is positioned at the back of the seat back. The ratchet is fixed to the upper arm, and is rotatably attached to the seat back frame. Accordingly, in a situation where an engagement of the latchet is released, the locked state is retained, and the seat back frame is rotated relatively to the latchet, the walk-in operation can be performed while the position of reclining angle adjustment is memorized.
However, in the configuration described in the patent document, in a situation where erroneous operations, such that the lock of the lock member is released at the time of the walk-in operation, is performed, the upper arm becomes freely rotatable with the ratchet out of relation to the rotational position of the seat back frame. By this, there is a danger that the walk-in operation is terminated by engaging the ratchet in a state where phases of rotational angles of the upper arm relative to the lower arm between a right side reclining apparatus and a left side reclining apparatus displace. Then, in a situation where next reclining operation of the seat back is performed in a state where the phase displaces as described above, operation's feeling is unpleasant.
Further, in the configuration described in the patent document, the ratchet is interposed between the upper arm and the seat back frame. However, in a configuration in which the ratchet is interposed between the lower arm and the cushion frame, similarly, the phase displacement described above induces an unpleasant feeling of the reclining operation. A need thus exists for a seat for a vehicle, in which walk-in operation is possible while a position of a reclining angle adjustment is memorized, and in which degradation of feeling of a reclining operation of a seat back can be inhibited. The present invention has been made in view of the above circumstances and provides such a seat for a vehicle.